Method and device for coating a body rotating about an axis

Abstract

The coating of bodies rotating about an axis with a reaction mixture forming a polyurethane can be improved by making use of a sheet die disposed parallel to the axis of rotation of the body at an angle α, whereby the rate of reaction of the reaction mixture and the relative movement are synchronized with the circumferential speed of the rotating body in such a way that the successive convolutions overlap in the form of scales and connect together seamlessly.

What is claimed is: 
     
       1. A method for coating a body comprising: i) rotating the body about an axis,   ii) ejecting a polyurethane reaction mixture through a sheet die onto said rotating body, with said sheet die being disposed at an angle α to said axis, and wherein the sheet die is maintained at a uniform distance of from 1 to 10 mm above the point at which said reaction mixture is applied to said rotating body,   iii) effecting relative movement between said rotating body and said sheet die in a direction parallel to said axis,   iv) synchronizing the rate of reaction of said reaction mixture and said relative movement with the circumferential speed of said rotating body in such a way that successive convolutions overlap in the form of scales and connect together seamlessly, and   v) wherein said circumferential speed is less than the speed at which said reaction mixture emerges from said sheet die.   
     
     
       2. The method of claim 1, wherein the angle α is adapted to the angle of a shoulder which is formed in the course of coating. 
     
     
       3. The method of claim 1, wherein said reaction mixture has a pouring-time of from 0.3 seconds to 10 minutes.